A substrate processing apparatus that executes a specific type of processing such as etching or film formation on a substrate such as a glass substrate (e.g., a liquid crystal substrate) or a semiconductor wafer (hereafter may be simply referred to as a “wafer”) includes a processing unit, achieved by connecting a loadlock chamber functioning as a relay chamber to a processing chamber where a wafer, for instance, undergoes the specific type of processing, and a transfer chamber through which a wafer is transferred (carried) into/out of the processing unit via a transfer mechanism such as a transfer arm.
In such a substrate processing apparatus, an unprocessed wafer stored in a cassette container is taken out and transferred over to the processing unit via the transfer mechanism at the transfer chamber. The unprocessed wafer is then carried into the processing chamber via the loadlock chamber and undergoes the specific type of processing such as etching in the processing chamber. Once the processing in the processing chamber ends, the processed wafer is carried back into the initial cassette container via the loadlock chamber from the processing chamber.
As the etching process or the like is executed on a wafer, particles constituted of reaction products or the like resulting from the etching process are generated inside the processing chamber. The particles adhering to the wafer cause shorting or the like in the wiring of the semiconductor devices manufactured by using the wafer, which ultimately leads to a poor yield. The quantity of particles adhering to the wafer changes depending upon the state and the like in each processing chamber. Accordingly, the state in the processing chamber must be inspected on a regular basis.
A method known in the related art for processing chamber state inspection executed by transferring a test-piece wafer, different from a product wafer, into an inspection target processing chamber and measuring the particles present on the test-piece wafer, has come to be adopted widely in recent years (e.g., see Japanese Laid Open Patent Publication No. 2006-179528).
However, it has been confirmed that depending upon the processing conditions under which the test-piece wafer is processed, the quantity of particles present on the test-piece wafer increases immediately after the processing or after a certain length of time elapses. For instance, if the test-piece wafer is processed at a low temperature equal to or lower than 0° C. (e.g., at −10° C. or lower), an increase in the quantity of particles assumed to be attributable to the moisture contained in the room air, occurs while the test-piece wafer is transferred from the loadlock chamber through the transfer chamber filled with room air.
The quantity of particles present on the test-piece wafer also increases immediately after the test-piece wafer is processed by using a processing gas containing a fluorocarbon gas and N2 gas or after the test-piece wafer having undergone such processing is returned into the cassette container and is left in the cassette container over a specific length of time or longer.
Since these phenomena result in an overall increase in the quantity of particles present on the test-piece wafer undergoes particle measurement, the quantity of particles having become adhered onto the test-piece wafer while the test-piece wafer was processed cannot be accurately measure. Thus, the state inside the processing chamber (e.g., the quantity of particles inside the processing chamber) cannot be inspected accurately.